Can brain stimulation deliver benefits?
What’s happening? University of California, San Francisco scientists have successfully used on-demand deep brain stimulation (DBS) to treat severe depression in a patient called Sarah. The team identified a neural biomarker that predicts onset of her symptoms, which allowed them to personalise a novel DBS device. This contained two leads, one implanted into the brain area where the biomarker is located and another in the depression circuit where stimulation most improved her symptoms. When the first lead identified the biomarker, the device signalled the other lead to deliver a low six-second dose of electricity to trigger change in neural activity to alleviate symptoms. (University of California, San Francisco, Nature Medicine)
Some background – For Sarah, the device has been life-changing, but it must be remembered she was the first patient to receive this technology for treatment-resistant depression and investigations involving other patients need to take place to gain a better understanding of its impact in the long term.
DBS itself, however, has previously been used to treat various illnesses, such as Parkinson’s disease, epilepsy, essential tremor, dystonia and obsessive-compulsive disorder. It’s also being investigated for other conditions including chronic pain, Tourette’s, Huntington’s and multiple sclerosis (MS).
Non-invasive stimulation – While surgery is required to implant DBS devices, there are non-invasive brain stimulation methods that hold promise for neurological and psychological issues in the pipeline. For example, a recent trial has found that transcranial direct current stimulation (tDCS) could boost cognitive function in older people suggesting it may help prevent age-related cognitive decline. Another has discovered that a similar technology called low frequency repetitive transcranial stimulation (rTMS) potentially improves memory performance.
A transcranial electrical stimulation (tES) device called StarStim developed by Neuroelectrics is also set to enter clinical trials for refractory focal epilepsy and as an at-home treatment for refractory depression. In the future this could be additionally used for Alzheimer’s disease, autism and attention-deficit hyperactivity disorder.
Although some way off yet, Rice University researchers aim to develop a device using methods such as machine learning, ultrasound stimulation and electromagnetic signalling to measure movement of cerebrospinal fluid (CSF) as it clears waste from the brain during sleep. The US Army is backing the project as it is interested in how lack of sleep can affect soldiers and if CSF modulation could enhance their performance. Such a device would also hold potential for the analysis and treatment of treatment of brain diseases and sleep disorders linked to neurodegenerative conditions.
What’s happening in the real world? rTMS and tDCS methods can be as treatments for depression, either alone or in combination with other therapies. NYU Langone Health is also using tDCS to help reduce cognitive, mood, motor and speech symptoms associated with disorders affecting the brain such as MS. It has recently introduced a home-use device based on the technology, which patients can use under virtual expert supervision accessed via an app.
In recent years, a slew of personal brain stimulation devices have come to market that don’t require a prescription. Many of these claim benefits such as improvements in sleep, blood flow, cognition, energy and pain reduction. There’s also headsets that can be bought off-the-shelf for depression. For example, Flow, which has EU approval, utilises tDCS alongside an companion app to help users make behavioural changes. The company suggests symptoms can be expected to improve within three weeks. Prices of such devices vary, but top-end products can cost upwards of £400 ($551) putting them out of reach people on lower-incomes.
The medical community is wary about the effectiveness of consumer brain stimulation devices, noting that trials are often small and with controls that are poor at excluding placebo effects. They are also concerned about potential long-term damage with unlicensed products and home-made devices. It’s also worth noting that when administered in a clinic, the provider will first check if such a treatment would be safe and effective for their patient.
Perhaps in the future, more effective personal brain stimulation devices will come to market based on more robust science. In the meantime, it would be better for the general population to maintain their wellbeing by following a healthy lifestyle rather than trying to zap themselves into it.
Lateral thought – The use of existing technologies against new indications or personalised treatments can cut time for them to become accessible due to less need for research and development and quicker regulatory approvals. The same can be said for drugs, with one of the most recent examples being how fluoxetine – better known as the antidepressant Prozac – has the potential to treat dry age-related macular degeneration, a leading cause of blindness in over-50s.